Originally Posted by Phaedrus
I will say right off that I'm a Japanese knife nut. Virtually all of my knives are Japanese save a few "legacy" blades and junkers that I have laying around. The knife case I take to work every day contains 10 J-knives. Overall Japanese knives based loosely on Western styles, like the gyuto, sujihiki and santoku (as well as American knives made in the style of Japanese ones, such as the Richmond lines) are much thinner, lighter and sharper than their European counterparts. The trade off is that they are perhaps not quite as robust as a German blade, although the difference is often overstated.
Let me first say that the term "stainless" is a misnomer. All steels can rust. Typically we call a steel "stainless" if it contains 13% or higher Chromium. Typical low end steels include 440C & AUS8. Although the blends are proprietary, nearly all the major German brands are building some some steel that's functionally the same as 440C. The baseline for mass market Japanese knives like Shun is VG-10 from Takefu Special Steels. Both are pretty stain resistant, but if you toss them in a bucket of strong bleach solution for a day or two you'll get rust. A coworker of mine lent his Tojiro DP to his uncle at Xmas as got it back 2 days later with some fine surface rust. VG-10 is very stainless (maybe 20% Cr?) so I was surprised. It almost had to have been from bleach.
I do understand that stainless is a misnomer. Anything with iron will rust under the right circumstances. I’d just like something that doesn’t rust under the circumstances found in our kitchen. "Stainless" steel is a lot like “bullet-proof” vests. They aren’t. There are just various grades of body armor rated to stop different types of projectiles, from low power handgun rounds up to ceramic ballistic plate inserts rated to stop 7.62mm AP rounds. Get hit with anything more than the vest rating and you’ll bleed.
One step removed from stainless is semi-stainless tool steels. The HD line from Konosuke and the Kagayaki CarboNext both use excellent tool steel. IIRC so does the fabled Aritsuga A-type. Tool steels vary from maker to maker but as a rule they don't rust easily. They will generally patina but not terribly so.
Since my original post I found the Zknives.com steel composition page and did some research. If the information there is correct (and I have no reason to doubt) it looks like all the steels I mentioned actually do qualify as stainless with a minimum of 13% Cr. Is there a similar limit that defines semi-stainless?
Since you earlier mentioned VG-10 specifically, it’s listed at 15.5% Cr. I’m really curious about what makes VG-10 so chippy. Its composition doesn’t seem to be that different from other stainless steels. Perhaps it’s the process. That seems to make a difference for CPM 154 as compared to CM 154. Is there a good source that describes how the various elemental components (other than Cr) affect the qualities of the resulting steel or is it not so cut-and-dried?
High Carbon is a catch all for steels that have low or no Chromium or other additives to prevent corrosion. In point of fact few "high carbon" contain more than around 1.7% carbon by weight; this is half of the carbon level present in ZDP-189, a very high end SS from Hitachi.
While on the subject of super-steels, you mentioned that you'd sharpened some M390 knives. Have you used M390 knives enough to form an opinion about it?
Steel is another things that deserves a book, not a short post, and I am neither a chemist nor a metallurgist. In a nutshell (and greatly oversimplifying things), Cr doesn't do anything to make a knife sharper, it mainly prevents corrosion (again, an oversimplification). As a general rule, high carbon/non-SS steels will have a finer grain structure and take a better edge. A very good carbon like Aogami (from Hitachi) will get much much sharper than, say, 440C and hold that edge a lot longer. Now, all carbons aren't created equal nor are all SS. For example, ZDP-189 will get almost as sharp as White #1 or Ao-Ko. But as a rule of thumb, you can generally say carbon will get sharper and is easier to sharpen that most SS.
Tool steels and PM steels muddy the waters somewhat. They can offer most of the advantages of carbon & SS while without the downsides of either. Ultimately, the heat treat is perhaps more important than the type of steel. And the steel isn't necessarily the most important factor in choosing a knife.
"Faux-Damascus" really doesn't bring anything to the table. Suminigashi, or "ink" (the fake dammie stuff) is just for appearance. There is some "real" Damascus out there but it's expensive and not relevant here. I agree that there's no reason to pay extra for it unless it's necessary to satisfy your SO. If a knife that I want happens to be clad in faux dammie that's not a reason to disqualify it though, either. For instance, I'd gladly take a Tanaka R2 in Ironwood.
Agreed. I think folded steel san-mai jigane or warikomi is pretty much just marketing to appeal to the less-educated customer. Of course, there’s nothing wrong with it if you like the look, either. Functional doesn’t require ugly.
There are two main reasons to clad a knife. The first is to cover a very reactive high carbon steel with stainless steel to prevent rust. Super Aogami is often clad for this reason. A knife so constructed will only have the HC exposed right at the very cutting edge. The second major reason (aside from appearance) is that the "Super Steels" used for the hagane (cutting core) are often very expensive. Cladding them cuts down on the cost. It can also support a more brittle steel and add some flexibility.
Years ago you needed to get HC if you wanted serious performance but this is no longer the case. There are lots of great SS knives nowadays. I would suggest though that you could cast your net wider. The tool steels, while only semi-SS, are generally pretty easy to maintain. None of mine have had any issues with red rust and patina only mildly. Also, there are some really good clad-carbon knives that are nearly as easy to maintain as full on SS.
I still want to stay away from carbon steel, even for the hagane, simply because I can’t be sure that the knives will always be cleaned promptly after use when I’m not around. Semi-stainless might be OK. I also suspect that carbon steel hagane might fall into the category of “I can’t tell the difference.”
But if you want SS, and it must be SS, then AEB-L is an excellent choice. All the numbers and nomenclature can be confusing, but it's a good steel. IIRC Sandvik makes families of similar SS steels that are great choices. While the exact steel isn't the biggest factor, overall I would avoid VG-10. It's ubiquitous and a decent steel, but can be chippy if not expertly heat treated. Hattori is regarded as a master of HT'ing VG-10, but few of the knives bearing the name are actually HT'd by Hattori. The HD line is produced by Ryu-sen and finished by Hattori. Actually, a helluva lot of big Japanese brands are OEM'd by lesser known Japanese companies, but that's at least a couple chapters if not a book unto itself.
AEB-L does look like a good choice for stainless, especially when compared to VG-10, and quite a few knives I've looked at use it.
Bottom line: Don't get hung up on what exact steel is being used and whether or not it's nominally stainless. All steel that contains iron can be made to rust, and the difficulty in preventing rust is greatly exaggerated.
Just in case you haven’t noticed , I tend to be pretty analytical, perhaps overly so. My problem with the semi-stainless steel knives is a lack of compositional information and/or standardized testing to determine the degree of stain resistance. I can’t get a good feel for them. There’s an investement maxim that goes “If you don’t understand it, don’t buy it.” I tend to think that’s good advice in other areas, too, including kitchen knives.
In the next post I'll address handles, types of knives and some actual brands.
I'm looking forward to it. Everything you've said so far is great and has been really helpful.